A known slide-type wireless terminal apparatus includes two casings, that is, a fixed casing and a movable casing. The movable casing is slidable relative to the fixed casing.
FIGS. 1A and 1B respectively illustrate a plan view and side view of an example of a slide-type wireless terminal apparatus in a casing-closed state, and FIG. 1C illustrates a side view of the example of the slide-type wireless terminal apparatus in a casing-open state.
A slide-type wireless terminal apparatus 1 includes a fixed casing 2 and a movable casing 3. The fixed casing 2 includes components such as a battery and an antenna 4. The movable casing 3 includes a display portion 5.
FIGS. 2A and 2B respectively illustrate sectional views of the example of the slide-type wireless terminal apparatus in the casing-open state and the casing-closed state.
The fixed casing 2 is provided with a slide module 7 in a surface that contacts the movable casing 3, and the movable casing 3 is provided with a rail plate 8 in a surface that contacts the fixed casing 2. The slide module 7 of the fixed casing 2 is engaged with the rail plate 8 of the movable casing 3 so as to allow the movable casing 3 to slide. Thus, the state of the slide-type wireless terminal apparatus 1 changes from the casing-open state illustrated in FIG. 2A to the casing-closed state illustrated in FIG. 2B, and from the casing-closed state to the casing-open state.
In the related art fixed casing 2, a distal end of the slide module 7 does not extend to the antenna 4 position in the Y direction, which is the longitudinal direction of the casing. The antenna 4 and the slide module 7 are disposed such that the slide module 7 and the antenna 4 do not oppose each other in the Z direction.
A technology is disclosed, in which an electrically conductive member is electrically connected to a ground pattern of a lower board and disposed at a position that is on a surface opposing a surface of the lower board in which an antenna element is disposed and that allows the electrically conductive member to be capacitively coupled to a flexible cable. In the technology, when a lower casing and an upper casing are closed, the electrically conductive member serves as a ground plate for the antenna element. In a slid open state, in which the upper casing has been slid relative to the lower casing, the electrically conductive member is capacitively coupled to the flexible cable so as to obtain an optimum capacitance as well as serving as a ground plate for the antenna element, thereby causing the current flowing in the lower board and the current flowing in the upper board to be in phase (refer to, for example, Japanese Laid-open Patent Publication No. 2009-194689).
A slide-type mobile phone including a board for operation portion having an antenna element formed on the board is also known (refer to, for example, Japanese Laid-open Patent Publication No. 2006-325098).
There is also a known technology in which a chip antenna is mounted on a board such that a power feeding terminal side of an antenna conductor overlaps a ground pattern, and a portion of the antenna that is closer to an end than the power feeding terminal side portion does not overlap the ground pattern. The chip antenna includes a meandering antenna conductor, and the portion of the meandering antenna conductor where the conductor is closely folded partially or entirely overlaps the ground pattern (refer to, for example, Japanese Laid-open Patent Publication No. 2002-314316).
As illustrated in FIG. 1C, the fixed casing 2 partially overlaps the movable casing 3 in the slide-type wireless terminal apparatus 1 in the casing-open state. When the case current (or image current) flows in the longitudinal direction of the casing, it is desirable that the current flowing in a board of the fixed casing 2 and the current flowing in a board of the movable casing 3 in the casing-open state are in phase, the currents flowing in the same direction as illustrated by the arrows in FIG. 3A.
However, in the 800 MHz frequency band, the current flowing in the board of the fixed casing 2 and the current flowing in the board of the movable casing 3 in the casing-open state are completely out of phase as illustrated by the arrows in FIG. 3B. This degrades the transmission/reception characteristics in many cases.
Effects that degrade the transmission/reception characteristics are reduced by increasing the distance between the fixed casing 2 and the movable casing 3. However, since the size and the thickness of terminal apparatuses are being increasingly reduced, maintaining a large distance between the casings would decrease competitiveness of the products.